Liquid crystal display device

ABSTRACT

The present invention provides a liquid crystal display device which can largely suppress the reduction of contrast which occurs in a light reflection mode of a liquid crystal display device. On a liquid-crystal-side surface of one of substrates which are arranged to face each other in an opposed manner while sandwiching liquid crystal therebetween, the liquid crystal display device includes pixel regions each of which is classified into a light reflection portion and a light transmission portion. On each pixel region, a first light-transmitting pixel electrode which is formed on the light reflection portion and the light transmission portion, a material layer which is formed on a major portion of the light reflection portion, an insulation layer having an opening formed at a portion corresponding to the light transmission portion, and a second pixel electrode which is formed on the light reflection portion and functions as a reflection film are sequentially laminated.

BACKGROUND OF THE INVENTION

[0001] The present invention relates to a liquid crystal display device,and more particularly to a so-called “partial transmission type” activematrix liquid crystal display device.

[0002] In an active matrix type liquid crystal display device, on aliquid-crystal-side surface of one of respective transparent substrateswhich are arranged to face each other in an opposed manner whilesandwiching liquid crystal therebetween, gate signal lines which areextended in the x direction and are arranged in the y direction inparallel and drain signal lines which are extended in the y directionand are arranged in the x direction in parallel are formed, and regionssurrounded by these respective signal lines are formed as pixel regions.

[0003] A thin film transistor which is driven by scanning signals from aone-side gate signal line and a pixel electrode to which video signalsare supplied from a one-side drain signal line through the thin filmtransistor are provided to each pixel region.

[0004] Further, with respect to such a liquid crystal display device, aso-called partial transmission type liquid crystal display deviceincludes a light transmission portion which constitutes a region whichallows light from a backlight disposed at a back surface side to passtherethrough and a light reflection portion which constitutes a regionin which an external light such as sun beams are reflected on each pixelregion.

[0005] The light transmission portion is formed of a region whichconstitutes the pixel electrode using a light-transmitting conductivelayer and the light reflection portion is formed of a region whichconstitutes the pixel electrode using a non-light-transmittingconductive layer having a light-reflecting function.

[0006] However, with respect to the liquid crystal display device havingsuch a constitution, it has been pointed out that the contrast ofdisplay is largely reduced particularly when the liquid crystal displaydevice is used in a light reflection mode.

[0007] As a result of the study of causes of such phenomenon, inventorsof the present invention have found that the pixel electrode which isformed on the light reflection portion is constituted of thenon-light-transmitting conductive layer and hence, a capacitive elementor the like is generated at a lower-layer side of the pixel region inmany cases whereby the height of the pixel electrode which alsofunctions as a reflection film differs with respect to a substrate.

[0008] The difference in height of the reflection film results in thedifference of layer thickness of liquid crystal in such portions andthis brings about the lowering of contrast.

[0009] For example, it has been known from a result of an experimentthat when the difference of 0.2 μm is generated with respect to theheight of the reflection film, the contrast is halved.

[0010] The present invention is made in view of such circumstances andit is an object of the present invention to provide a liquid crystaldisplay device which can enhance the contrast.

SUMMARY OF THE INVENTION

[0011] To simply explain the summary of typical examples amonginventions which are disclosed in the specification, they are asfollows.

Means 1

[0012] A liquid crystal display device according to the presentinvention includes, for example, pixel regions each of which is dividedinto a light reflection portion and a light transmission portion on aliquid-crystal-side surface of one substrate out of substrates which arearranged to face each other in an opposed manner while sandwichingliquid crystal therebetween, wherein

[0013] on each pixel region, a first light-transmitting pixel electrodewhich is formed on the light reflection portion and the lighttransmission portion, a material layer which is formed on a majorportion of the light reflection portion, an insulation layer in which anopening is formed at the light transmission portion, and a second pixelelectrode which is formed on the light reflection portion and alsofunctions as a reflection film are sequentially laminated.

Means 2

[0014] A liquid crystal display device according to the presentinvention includes, for example, pixel regions each of which is dividedinto a light reflection portion and a light transmission portion on aliquid-crystal-side surface of one substrate out of substrates which arearranged to face each other in an opposed manner while sandwichingliquid crystal therebetween, wherein

[0015] the pixel region is formed as a region which is surrounded by apair of gate signal lines and a pair of drain signal lines and includesa thin film transistor which is operated in response to scanning signalsfrom one gate signal line out of the pair of gate signal lines and firstand second pixel electrodes to which video signals from one drain signalline out of the pair of drain signal lines are supplied through the thinfilm transistor, and

[0016] on each pixel region, the first light-transmitting pixelelectrode which is formed on the light reflection portion and the lighttransmission portion, a material layer which is formed on a majorportion of the light reflection portion, an insulation layer in which anopening is formed at the light transmission portion, and the secondpixel electrode which is formed on the light reflection portion and alsofunctions as a reflection film are sequentially laminated.

Means 3

[0017] A liquid crystal display device according to the presentinvention includes, for example, pixel regions each of which is dividedinto a light reflection portion and a light transmission portion on aliquid-crystal-side surface of one substrate out of substrates which arearranged to face each other in an opposed manner while sandwichingliquid crystal therebetween, wherein

[0018] the pixel region is formed as a region which is surrounded by apair of gate signal lines and a pair of drain signal lines and includesa thin film transistor which is operated in response to scanning signalsfrom one gate signal line out of the pair of gate signal lines and firstand second pixel electrodes to which video signals from one drain signalline out of the pair of drain signal lines are supplied through the thinfilm transistor,

[0019] on each pixel region, the first light-transmitting pixelelectrode which is formed on the light reflection portion and the lighttransmission portion, a material layer which is formed on a majorportion of the light reflection portion, an insulation layer in which anopening is formed at the light transmission portion, and the secondpixel electrode which is formed on the light reflection portion and alsofunctions as a reflection film are sequentially laminated, and

[0020] a total layer thickness of the first pixel electrode and thematerial layer and a layer thickness of the gate signal line arerespectively set to equal to or less than 100 nm.

Means 4

[0021] A liquid crystal display device according to the presentinvention includes, for example, pixel regions each of which is dividedinto a light reflection portion and a light transmission portion on aliquid-crystal-side surface of one substrate out of substrates which arearranged to face each other in an opposed manner while sandwichingliquid crystal therebetween, wherein

[0022] the pixel region is formed as a region which is surrounded by apair of gate signal lines and a pair of drain signal lines and includesa thin film transistor which is operated in response to scanning signalsfrom one gate signal line out of the pair of gate signal lines and firstand second pixel electrodes to which video signals from one drain signalline out of the pair of drain signal lines are supplied through the thinfilm transistor,

[0023] on each pixel region, the first light-transmitting pixelelectrode which is formed on the light reflection portion and the lighttransmission portion, a material layer which is formed on a majorportion of the light reflection portion, an insulation layer in which anopening is formed at the light transmission portion, and the secondpixel electrode which is formed on the light reflection portion and alsofunctions as a reflection film are sequentially laminated, and

[0024] the difference between a total layer thickness of the first pixelelectrode and the material layer and a layer thickness of the gatesignal line is set to equal to or less than 0.1 μm.

Means 5

[0025] A liquid crystal display device according to the presentinvention includes, for example, pixel regions each of which is dividedinto a light reflection portion and a light transmission portion on aliquid-crystal-side surface of one substrate out of substrates which arearranged to face each other in an opposed manner while sandwichingliquid crystal therebetween, wherein

[0026] the pixel region is formed as a region which is surrounded by apair of gate signal lines and a pair of drain signal lines and includesa thin film transistor which is operated in response to scanning signalsfrom one gate signal line out of the pair of gate signal lines and firstand second pixel electrodes to which video signals from one drain signalline out of the pair of drain signal lines are supplied through the thinfilm transistor, and

[0027] on each pixel region, the first light-transmitting pixelelectrode which is formed on the light reflection portion and the lighttransmission portion, an extension layer of a source electrode of thethin film transistor which is connected to the first pixel electrode andis formed on a major portion of the light reflection portion, aninsulation layer in which an opening is formed at the light transmissionportion, and the second pixel electrode which is formed on the lightreflection portion, is connected to the source electrode through acontact hole formed in the insulation layer and also functions as areflection film are sequentially laminated.

Means 6

[0028] A liquid crystal display device according to the presentinvention includes, for example, pixel regions each of which is dividedinto a light reflection portion and a light transmission portion on aliquid-crystal-surface side of one substrate out of substrates which arearranged to face each other in an opposed manner while sandwichingliquid crystal therebetween, wherein

[0029] the pixel region is formed as a region which is surrounded by apair of gate signal lines and a pair of drain signal lines and includesa thin film transistor which is operated in response to scanning signalsfrom one gate signal line out of the pair of gate signal lines and firstand second pixel electrodes to which video signals from one drain signalline out of the pair of drain signal lines are supplied through the thinfilm transistor,

[0030] on each pixel region, the first light-transmitting pixelelectrode which is formed on the light reflection portion and the lighttransmission portion, an extension layer of a source electrode of thethin film transistor which is connected to the first pixel electrode andis formed on a major portion of the light reflection portion, aninsulation layer in which an opening is formed at the light transmissionportion, and the second pixel electrode which is formed on the lightreflection portion, is connected to the source electrode through acontact hole formed in the insulation layer and also functions as areflection film are sequentially laminated, and the difference between atotal layer thickness of the first pixel electrode and the extensionlayer of the source electrode and a layer thickness of the gate signalline is set to equal to or less than 0.1 μm.

Means 7

[0031] A liquid crystal display device according to the presentinvention includes, for example, pixel regions each of which is dividedinto a light reflection portion and a light transmission portion on aliquid-crystal-side surface of one substrate out of substrates which arearranged to face each other in an opposed manner while sandwichingliquid crystal therebetween, wherein

[0032] the pixel region is formed as a region which is surrounded by apair of gate signal lines and a pair of drain signal lines and includesa thin film transistor which is operated in response to scanning signalsfrom one gate signal line out of the pair of gate signal lines and firstand second pixel electrodes to which video signals from one drain signalline out of the pair of drain signal lines are supplied through the thinfilm transistor,

[0033] on each pixel region, the first light-transmitting pixelelectrode which is formed on the light reflection portion and the lighttransmission portion, a material layer which is formed on a majorportion of the light reflection portion, an insulation layer in which anopening is formed at the light transmission portion, and the secondpixel electrode which is formed on the light reflection portion and alsofunctions as a reflection film are sequentially laminated, and

[0034] the second pixel electrode is formed in a superposed manner onthe other gate signal line out of the pair of gate signal lines.

Means 8

[0035] A liquid crystal display device according to the presentinvention includes, for example, pixel regions each of which is dividedinto a light reflection portion and a light transmission portion on aliquid-crystal-side surface of one substrate out of substrates which arearranged to face each other in an opposed manner while sandwichingliquid crystal therebetween, wherein

[0036] the pixel region is formed as a region which is surrounded by apair of gate signal lines and a pair of drain signal lines and includesa thin film transistor which is operated in response to scanning signalsfrom one gate signal line out of the pair of gate signal lines and firstand second pixel electrodes to which video signals from one drain signalline out of the pair of drain signal lines are supplied through the thinfilm transistor,

[0037] on each pixel region, the first light-transmitting pixelelectrode which is formed on the light reflection portion and the lighttransmission portion, a material layer which is formed on a majorportion of the light reflection portion, an insulation layer in which anopening is formed at the light transmission portion, and the secondpixel electrode which is formed on the light reflection portion and alsofunctions as a reflection film are sequentially laminated, and

[0038] the second pixel electrode is formed in a superposed manner onthe other gate signal line out of the pair of gate signal lines, and aheight adjusting material which is provided for setting the differencebetween a height of the second pixel electrode with respect to thesubstrate in the light reflection portion and a height of the secondpixel electrode which is formed in a superposed manner on the other gatesignal line with respect to the substrate to equal to or less than 0.1μm is interposed at at least one of the light reflection portion and theother gate signal line.

Means 9

[0039] A liquid crystal display device according to the presentinvention includes, for example, pixel regions each of which is dividedinto a light reflection portion and a light transmission portion on aliquid-crystal-side surface of one substrate out of substrates which arearranged to face each other in an opposed manner while sandwichingliquid crystal therebetween, wherein

[0040] the pixel region is formed as a region which is surrounded by apair of gate signal lines and a pair of drain signal lines and includesa thin film transistor which is operated in response to scanning signalsfrom one gate signal line out of the pair of gate signal lines and firstand second pixel electrodes to which video signals from one drain signalline out of the pair of drain signal lines are supplied through the thinfilm transistor, and

[0041] on each pixel region, the first light-transmitting pixelelectrode which is formed on the light reflection portion and the lighttransmission portion, a material layer which is formed on a majorportion of the light reflection portion, an insulation layer which isformed on the light reflection portion and the light transmissionportion, and the second pixel electrode which is formed on the lightreflection portion and also functions as a reflection film aresequentially laminated.

Means 10

[0042] A liquid crystal display device according to the presentinvention includes, for example, pixel regions each of which is dividedinto a light reflection portion and a light transmission portion on aliquid-crystal-side surface of one substrate out of substrates which arearranged to face each other in an opposed manner while sandwichingliquid crystal therebetween, wherein

[0043] the pixel region is formed as a region which is surrounded by apair of gate signal lines and a pair of drain signal lines and includesa thin film transistor which is operated in response to scanning signalsfrom one gate signal line out of the pair of gate signal lines and firstand second pixel electrodes to which video signals from one drain signalline out of the pair of drain signal lines are supplied through the thinfilm transistor,

[0044] on each pixel region, the first light-transmitting pixelelectrode which is formed on the light reflection portion and the lighttransmission portion, a material layer which is formed on a majorportion of the light reflection portion, an insulation layer which isformed on the light reflection portion and the light transmissionportion, and the second pixel electrode which is formed on the lightreflection portion and also functions as a reflection film aresequentially laminated, and

[0045] the difference between a total layer thickness of the first pixelelectrode and the material layer and a layer thickness of the gatesignal line is set to equal to or less than 0.1 μm.

Means 11

[0046] A liquid crystal display device according to any one of the means1 to the means 10 includes, for example, a backlight.

BRIEF DESCRIPTION OF THE DRAWINGS

[0047]FIG. 1 is a plan view showing one embodiment of a pixel of aliquid crystal display device according to the present invention.

[0048]FIG. 2 is a plan view showing one embodiment of an equivalentcircuit of the whole liquid crystal display device according to thepresent invention.

[0049]FIG. 3 is a cross-sectional view taken along a line III-III ofFIG. 1.

[0050]FIG. 4A to FIG. 4F are process flow views showing one embodimentof a manufacturing method of the liquid crystal display device accordingto the present invention.

[0051]FIG. 5 is a cross-sectional view showing another embodiment of thepixel of the liquid crystal display device according to the presentinvention.

[0052]FIG. 6 is a cross-sectional view showing another embodiment of thepixel of the liquid crystal display device according to the presentinvention.

[0053]FIG. 8 is a cross-sectional view showing another embodiment of thepixel of the liquid crystal display device according to the presentinvention.

[0054]FIG. 9 is a cross-sectional view showing another embodiment of thepixel of the liquid crystal display device according to the presentinvention.

[0055]FIG. 9 is a cross-sectional view showing another embodiment of thepixel of the liquid crystal display device according to the presentinvention.

[0056]FIG. 10A to FIG. 10B are plan views showing other embodiments of apixel electrode which also functions as a reflection electrode of theliquid crystal display device of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0057] Embodiments of a liquid crystal display device according to thepresent invention are explained in detail in conjunction with drawingshereinafter.

Overall Equivalent Circuit

[0058]FIG. 2 is a plan view showing one embodiment of an overallequivalent circuit of a liquid crystal display device according to thepresent invention.

[0059] In the drawing, there are shown a pair of transparent substratesSUB1, SUB2 which are arranged to face each other in an opposed mannerwhile inserting liquid crystal therebetween. The liquid crystal filledin a space defined between a pair of transparent substrates SUB1, SUB2is sealed by a sealing member SL which is also served for fixing theother transparent substrate SUB2 to one transparent substrate SUB1.

[0060] On a liquid-crystal-side surface of one transparent substrateSUB1 which is surrounded by the sealing member SL, gate signal lines GLwhich are extended in the x direction and are arranged in the ydirection in parallel and drain signal lines DL which are extended inthe y direction and are arranged in the x direction in parallel areformed.

[0061] Regions which are surrounded by respective gate signal lines GLand respective drain signal lines DL constitute pixel regions and aliquid crystal display part AR is constituted by a mass of theserespective pixel regions arranged in a matrix array.

[0062] On each pixel region, a thin film transistor TFT which isoperated by the supply of scanning signals from the one-side gate signalline GL and a pixel electrode PX to which video signals are suppliedfrom the one-side drain signal line DL by way of the thin filmtransistor TFT are formed.

[0063] The pixel electrode PX forms a capacitive element Cadd betweenthe pixel electrode PX and other gate signal line GL which is differentfrom the gate signal line GL for driving the thin film transistor TFT.Due to this capacitive element Cadd, the video signals supplied to thepixel electrode PX are stored for a relatively long time.

[0064] The pixel electrode PX in each pixel region is configured togenerate an electric field between the pixel electrode PX and a counterelectrode CT which is formed in common with respective pixel regions onthe other transparent substrate SUB2. The light transmittivity of theliquid crystal can be controlled in response to this electric field.

[0065] Respective ends of the gate signal lines GL are extended over thesealing member SL and the extended end constitute terminals to whichoutput terminals of a vertical scanning driving circuit V are connected.Further, signals from a printed circuit board which is arranged outsidethe liquid crystal display device are inputted to input terminals of thevertical scanning driving circuit V.

[0066] The vertical scanning driving circuit V includes a plurality ofsemiconductor devices, wherein a plurality of neighboring gate signallines GL are formed into a group and one semiconductor device isallocated to each group.

[0067] Respective ends of the drain signal lines DL are extended overthe sealing member SL and the extended ends constitute terminals towhich output terminals of a video signal driving circuit He areconnected. Further, signals from the printed circuit board which isarranged outside the liquid crystal display device are inputted to inputterminals of the video signal driving circuit He.

[0068] This video signal driving circuit He also includes a plurality ofsemiconductor devices, wherein a plurality of neighboring drain signallines DL are formed into a group and one semiconductor device isallocated to each group.

[0069] Respective gate signal lines GL are sequentially selected one byone in response to the scanning signals from the vertical scanningdriving circuit V.

[0070] Further, the video signals are supplied to respective drainsignal lines DL by the video signal driving circuit He while beingmatched with the timing of the selection of the gate signal lines GL.

[0071] A backlight BL is mounted on a back surface of the liquid crystaldisplay device having such a constitution and this light source isturned on when the liquid crystal display device is used in atransmission mode.

[0072] Although the vertical scanning driving circuit V and the videosignal driving circuit He are respectively mounted on the transparentsubstrate SUB1 in this embodiment, it is needless to say that thepresent invention is not limited to such a constitution and thesecircuits V, He may be provided outside the transparent substrate SUB1.

Constitution of Pixels

[0073]FIG. 1 is a plan view showing one embodiment of the pixel regions.Although respective pixels for R, G and B are shown in the drawing aspixels for color display, they only differ in color of color filters andhave the same constitution.

[0074] Following explanation is made by focusing on one pixel out ofthese three pixels. A cross section taken along a line III-III in thedrawing is shown in FIG. 3.

[0075] In the drawing, on a liquid-crystal-side surface of thetransparent substrate SUB1, first of all, a pair of gate signal lines GLwhich are extended in the x direction and are arranged in parallel inthe y direction are formed. These gate signal lines GL are, for example,made of Al (aluminum) and anodic oxidation films AOF are formed onsurfaces of the gate signal lines GL.

[0076] These gate signal lines GL surround a rectangular region togetherwith a pair of drain signal lines DL which will be explained later andthis region constitutes a pixel region.

[0077] A light-transmitting pixel electrode PX1 formed of an ITO(Indium—Tin—Oxide) film, for example, is formed on a central portion ofthe pixel region except for a trivial peripheral portion.

[0078] The pixel electrode PX1 functions as a pixel electrode in aregion of the pixel region which allows light from a backlight BL topass therethrough and is classified from a pixel electrode PX2 whichalso functions as a reflection electrode as will be explained later.

[0079] On the surface of the transparent substrate SUB1 on which thegate signal lines GL and the pixel electrodes PX1 are formed, aninsulation film GI made of, for example, SiN (silicon nitride) isformed. The insulation film GI is formed such that the insulation filmGI is extended over regions where thin film transistors TFT are formed(partial regions of gate signal lines GL) and portions where the gatesignal lines GL and the drain signal lines DL cross each other arrangedin the vicinity of the thin-film-transistor forming regions.

[0080] The insulation film GI which is formed over the regions wherethin film transistors TFT are formed functions as a gate insulation filmof the thin film transistors TFT and the insulation film GI which isformed over the portions where the gate signal lines GL and the drainsignal lines DL cross each other functions as an interlayer insulationfilm.

[0081] On a surface of the insulation film GI, a semiconductor layer ASmade of amorphous Si (silicon) is formed.

[0082] The semiconductor layer AS constitutes a semiconductor layer ofthe thin film transistor TFT. That is, by forming a drain electrode SD1and a source electrode SD2, an MIS transistor having an inverse staggerstructure which uses a portion of the gate signal line GL as a gateelectrode can be formed.

[0083] The semiconductor layer AS is formed such that the semiconductorlayer AS is also extended over the portion where the gate signal line GLand the drain signal line DL cross each other thus strengthening thefunction of these signal lines as the interlayer insulation filmtogether with the insulation film GI.

[0084] Further, although not shown in the drawing, above the surface ofthe semiconductor layer AS and in a boundary between the drain electrodeSD1 and the source electrode SD2, a semiconductor layer doped withimpurity (for example, phosphorus) of high concentration is formed and acontact layer d0 is formed of this semiconductor layer.

[0085] The drain electrode SD1 and the source electrode SD2 are formedsimultaneously with the formation of the drain signal lines DL.

[0086] That is, the drain signal lines DL which are extended in the ydirection and are arranged in parallel in the x direction are formed, aportion of each drain signal line DL is extended over an upper surfaceof the semiconductor layer AS thus forming the drain electrode SD1, andthe source electrode SD2 is formed spaced apart from the drain electrodeSD1 by a channel length of the thin film transistor TFT.

[0087] The drain signal line DL is constituted of a sequentiallylaminated body made of Cr and Al, for example.

[0088] The source electrode SD2 is slightly extended from thesemiconductor layer AS surface such that the source electrode SD2reaches the pixel region side thus establishing the electric connectionbetween the source electrode SD2 and the pixel electrode PX1. Further,the source electrode SD2 is provided with a contact portion to establishthe electric connection between the source electrode SD2 and the pixelelectrode PX2 which also functions as a reflection electrode as will beexplained later.

[0089] Here, the extension portion of the source electrode SD2 not onlyperforms the function of connecting the source electrode SD2 to thepixel electrodes PX1 and PX2 as mentioned above but also is extendedover a major portion of a light reflection portion (region where thepixel electrode PX2 is formed as will be explained later) such that thedifference in height due to a step does not appear remarkably in thepixel electrode PX2 in the light reflection portion.

[0090] That is, when the extension portion of the source electrode SD2is provided with only the function of connecting the source electrodeSD2 to the pixel electrodes PX1 and PX2, the extension portion may beformed as a contact portion and the extension portion becomes relativelyshort. Accordingly, a step formed around the extension portionexplicitly appears remarkably on a surface which forms the pixelelectrode PX2 which also functions as the reflection electrode as willbe explained later (upper surface of a protective film PSV which will beexplained later) so that a step is also formed on a surface of the pixelelectrode PX2.

[0091] Further, with the use of the constitution of this embodiment, theextension portion of the source electrode SD2 occupies a region ofrelatively large area and this implies that the side is relativelyelongated.

[0092] Accordingly, in the fabrication of the liquid crystal displaydevice, impurities such as dusts hardly remains in the vicinity of thepixel electrode PX2 so the drawbacks derived from the impurities can beobviated.

[0093] Here, when the gate electrode of the thin film transistor TFTfunctions as the contact portion, the area of the contact portion issmall and the side thereof is formed in a slightly complicated mannerdue to the selective etching using a photolithography technique andhence, impurities such as dusts remain here so that the function of thegate electrode as the contact portion has been often damaged.

[0094] Over the surface of the transparent substrate SUB1 on which thedrain signal lines DL and the drain electrodes SD1 and the sourceelectrodes SD2 of the thin film transistors TFT are formed, a protectivefilm PSV made of SiN, for example, is formed. This protective film PSVis a layer which obviates the direct contact of the thin film transistorTFT with the liquid crystal LC and is served for preventing thedeterioration of the characteristics of the thin film transistors TFT.

[0095] In portions of the protective film PSV which correspond to thelight transmission portions of the pixel regions, opening portions OMare formed. The light-transmitting pixel electrodes PX1 are exposedthrough these opening portions OM. The opening portions OM of theprotective film PSV through which the pixel electrode PX1 is exposed areregions which constitute the light transmission portions and defineregions which are classified from the regions of the light reflectionportions in the pixel regions.

[0096] Further, in the protective film PSV, the contact holes CH whichare formed simultaneously with the formation of the opening portions OMare formed. A portion of the source electrode SD2 of the thin filmtransistor TFT is exposed through each contact hole CH.

[0097] On an upper surface of the protective film PSV, the pixelelectrodes PX2 which also function as the reflection electrodes areformed. Each pixel electrode PX2 is formed of a non-light transmittingconductive film consisting of a sequential laminating body made of Crand Al, for example.

[0098] The pixel electrode PX2 is formed such that the pixel electrodePX2 occupies a major portion of the pixel region while avoiding theregion where the opening portion OM is formed in the protective filmPSV.

[0099] Then, the pixel electrode PX2 has a portion thereof electricallyconnected to the source electrode SD2 of the thin film transistor TFTthrough the contact hole CH which is partially formed in the portion ofthe protective film PSV.

[0100] Further, the pixel electrode PX2 is formed such that the pixelelectrode PX2 is extended to a position where the pixel electrode PX2 issuperposed on other neighboring gate signal line GL which is differentfrom the gate signal line GL for driving the above-mentioned thin filmtransistor TFT. A capacitive element Cadd which uses the protective filmPSV as an dielectric film is formed in the extension portion of thepixel electrode PX2.

[0101] Over the upper surface of the transparent substrate SUB1 on whichthe pixel electrodes PX2 are formed, an orientation film (not shown inthe drawing) is formed such that the orientation film also covers thepixel electrodes PX2 and the like. The orientation film is a film whichis directly brought into contact with the liquid crystal LC anddetermines the initial orientation direction of molecules of the liquidcrystal LC by rubbing a surface thereof.

[0102] The transparent substrate SUB2 is arranged to face thetransparent substrate SUB1 having such a constitution in an opposedmanner while sandwiching the liquid crystal therebetween. On aliquid-crystal-side surface of the transparent substrate SUB2, a blackmatrix BM is formed such that the black matrix BM defines respectivepixel regions. That is, the black matrix BM which is formed over atleast the liquid crystal display part AR is provided with a patternwhich forms openings except for peripheral portions of respective pixelregions thus enhancing the contrast of display.

[0103] Further, the black matrix BM is formed such that the black matrixBM sufficiently covers the thin film transistors TFT of the transparentsubstrate SUB1 side so that it is possible to prevent an external lightfrom being irradiated to the thin film transistors TFT whereby thedeterioration of the characteristics of the thin film transistors TFTcan be obviated. The black matrix BM is formed of a resin film whichcontains black pigment therein, for example.

[0104] Over the surface of the transparent substrate SUB2 on which theblack matrix BM is formed, color filters FIL are formed such that thesecolor filters FIL cover the openings formed in the black matrix BM.These color filters FIL are constituted of filters of respective colorsconsisting of red (R), green (G) and blue (B), for example. Here, thered filter, for example, is formed in common with respect to a group ofrespective pixel regions which are arranged in parallel in the ydirection, while with respect to such groups of pixel regions which arearranged in the x direction, they are sequentially arranged in the orderof red (R), green (G), blue (B), red (R), . . . . These respectivefilters are formed of resin films which contain pigments correspondingto respective colors.

[0105] Over the surface of the transparent substrate SUB2 on which theblack matrix BM and the color filters FIL are formed, a flattening filmOC is formed such that the flattening film OC also covers the blackmatrix BM and the color filters FIL. The flattening film OM is a resinfilm which is formed by coating and is served for eliminating stepswhich become apparent due to the formation of the black matrix BM andthe color filters FIL.

[0106] Over an upper surface of the flattening film OC, a lighttransmitting conductive film made of an ITO film, for example, isformed. With the provision of this conductive film, a counter electrodeCT which corresponds to respective pixel regions in common is formed.

[0107] Over a surface of the flattening film OC, an orientation film(not shown in the drawing) is formed. The orientation film is a filmwhich is directly brought into contact with the liquid crystal LC anddetermines the initial orientation direction of molecules of the liquidcrystal LC by rubbing a surface thereof.

[0108] In the liquid crystal display device having such a constitution,the source electrode SD2 of each thin film transistor TFT is formed suchthat the source electrode SD2 is extended to a region corresponding tothe light reflection portion of the pixel region.

[0109] Accordingly, the pixel electrode PX2 which is formed on the lightreflection portion by way of the protective film PSV can be formed in aflattened shape with no difference in height derived from the steps.

[0110] This enables the liquid crystal to have a uniform layer thicknessin the light reflection portion so that the irregularities of contrastwhich is generated due to the irregularities of the layer thickness canbe drastically suppressed.

[0111] Further, although it is not directly relevant to the lightreflection portion, the height of the pixel electrode PX2 with respectto the transparent substrate SUB1 in the portion where the capacitiveelement Cadd is formed can be set substantially equal to the height ofthe pixel electrode PX2 with respect to the transparent substrate SUB1in the light reflection portion.

[0112] Although a portion on which the capacitive element Cadd is formedconstitutes a portion covered with the black matrix BM, at a portionwhich is disposed in the inside of the opening of the black matrix BMand is disposed close to the capacitive element Cadd, it is possible toprevent the generation of the influence derived from the difference inheight of the pixel electrode PX2 with respect to the transparentsubstrate SUB1.

[0113] Accordingly, by respectively setting “a layer thickness of thegate signal line GL” and “a total layer thickness of the sourceelectrode SD2 of the pixel electrode PX1 and the thin film transistorTFT” to equal to or less than 100 nm, it is possible to suppress theirregularities of height of the pixel electrode PX2 with respect to thetransparent substrate SUB1 as small as possible.

[0114] Then, by setting the difference between “the layer thickness ofthe gate signal line GL” and “the total layer thickness of the sourceelectrode SD2 of the pixel electrode PX1 and the thin film transistorTFT” to equal to or less than 0.1 μm, it is possible to restrict theirregularities of height of the pixel electrode PX2 with respect to thetransparent substrate SUB1 to equal to or less than 0.1 μm.

[0115] Due to such a constitution, the layer thickness of the liquidcrystal LC can be substantially made uniform in the light reflectionportion of the pixel region and hence, the reduction of the contrast canbe suppressed.

[0116] In the above-mentioned embodiment, the source electrode SD2 ofeach thin film transistor TFT is sufficiently extended over the lightreflection portion so as to prevent the generation of steps of the pixelelectrode PX2 which is formed on the source electrode SD2.

[0117] However, it is needless to say that the same advantageous effectcan be obtained by using other material layer which is electrically (orphysically) separated from the source electrode SD2.

[0118] In this case, since the film thickness of the material layer canbe set irrespective of the source electrode SD2 of the thin filmtransistor TFT, an advantageous effect that the flattening of the pixelelectrode PX2 can be easily achieved is obtained.

Fabricating Method

[0119] Hereinafter, one embodiment of the fabricating method of thetransparent-substrate-SUB1 side of the above-mentioned liquid crystaldisplay device is explained in conjunction with FIG. 4A to FIG. 4F.

Step 1. (FIG. 4A)

[0120] The transparent substrate SUB1 was prepared and an Al film havinga film thickness of approximately 260 nm was formed on a main surface(liquid-crystal-side surface) of the transparent substrate SUB1 by asputtering method, for example. Then, the Al film was selectively etchedusing a photolithography technique so as to form the gate signal linesGL.

[0121] Then, the gate signal lines GL were subjected to the anodicoxidation in a tartaric acid solution so as to form anodic oxidationfilms AOF on the gate signal lines GL. It is preferable to set a filmthickness of the anodic oxidation films AOF to approximately 154 nm.

Step 2. (FIG. 4B)

[0122] On the main surface of the transparent substrate SUB1 on whichthe gate signal lines GL were formed, a light-transmitting conductivefilm formed of an ITO (Indium—Tin—Oxide) film, for example, was formedand the conductive film was selectively etched by a photolithographytechnique so as to form the pixel electrodes PX1.

Step 3. (FIG. 4C)

[0123] The insulation film made of SiN having a film thickness ofapproximately 240 nm was formed on the main surface of the transparentsubstrate SUB1 on which the pixel electrodes PX1 were formed using a CVDmethod, for example. In the same manner, an amorphous silicon layerhaving a film thickness of approximately 200 nm was formed on theinsulation film and, thereafter, an n⁺-type amorphous silicon layerdoped with phosphorus (P) and having a film thickness of approximately35 nm was formed on the amorphous silicon film.

[0124] Then, the selective etching was performed using aphotolithography technique to etch the semiconductor layer and theinsulation film together so as to form the insulation film GI and thesemiconductor layers AS. As such an etching, a dry etching which uses asulfur hexafluoride gas is suitable.

[0125] Here, since the etching speed of the amorphous silicon is greaterthan the etching speed of the insulation film, a normal taper having anangle of approximately 40° is provided to sides which constitute aprofile of the insulation film GI and a normal taper having an angle ofapproximately 70° is provided to sides which constitute a profile of thesemiconductor layer AS.

Step 4. (FIG. 4D)

[0126] A Cr layer and an Al layer were sequentially formed on the mainsurface of the transparent substrate SUB1 on which the insulation filmGI and the semiconductor layers AS were formed using a sputteringmethod, for example. Here, it is preferable to set a film thickness ofthe Cr layer to 30 nm and a film thickness of the Al layer to 200 nm.

[0127] Thereafter, the selective etching was performed using aphotolithography technique so as to form the drain signal lines DL andthe drain electrodes SD1 and the source electrodes SD2 of the thin filmtransistors TFT having a two-layered structure.

[0128] Here, it is preferable to use a mixed solution of phosphoricacid, hydrochloric acid and nitric acid as an etchant for Al, while itis preferable to use a cerium nitrate ammonium solution as an etchantfor Cr.

[0129] Then, using the drain electrodes SD1 and the source electrodesSD2 of the patterned thin film transistors TFT as masks, the n⁺-typeamorphous silicon layers formed on the surface of the semiconductorlayers AS exposed from the masks were etched. Here, it is preferable toadopt a dry etching which uses a sulfur hexafluoride gas as an etchant.

Step 5. (FIG. 4E)

[0130] On the main surface of the transparent substrate SUB1 on whichthe drain signal lines DL and the drain electrodes SD1 and the sourceelectrodes SD2 of the thin film transistors TFT were formed, an SiN filmhaving a film thickness of approximately 600 nm was formed using a CVDmethod, for example, and the SiN film was selectively etched using aphotolithography technique to form the protective film PSV.

[0131] In performing such an etching, the contact holes CH which exposethe portions of the extension portions of the source electrodes SD2 ofthe thin film transistors TFT were simultaneously formed.

Step 6. (FIG. 4F)

[0132] A Cr layer and an Al layer were sequentially formed on the mainsurface of the transparent substrate SUB1 on which the protection filmPSV was formed using a sputtering method, for example. Then, the Crlayer and the Al layer were selectively etched using a photolithographytechnique to form the pixel electrodes PX2 which also function as thereflection electrodes.

[0133] Here, it is preferable to use a mixed solution of phosphoricacid, hydrochloric acid and nitric acid as an etchant for Al, while itis preferable to use an ammonium cerium nitrate solution as an etchantfor Cr.

[0134] In this case, openings were formed in the pixel electrodes PX2such that each opening occupies approximately a half of the pixelregion.

[0135] Thereafter, openings were formed on portions of the protectivefilms PSV which were exposed from the openings of the pixel electrodesPX2 so as to expose the pixel electrodes PX1 as shown in FIG. 3, whereinthese portions constitute the light transmission portions.

[0136] In place of sequentially forming the Cr layer and the Ar layer toform the pixel electrodes PX2, a Mo alloy layer and an Al layer may besequentially formed or a Mo alloy layer and an Al alloy layer may besequentially formed. It is preferable to use MoCr as the Mo alloy. Thisis advantageous since the etching can be performed at one time.

Embodiment 2

[0137]FIG. 5 is a constitutional view showing another embodiment of theliquid crystal display device of the present invention and correspondsto FIG. 3 which shows the constitution of the embodiment 1.

[0138] In constitution, this embodiment differs from the embodiment 1shown in FIG. 3 in that material layers DML for adjusting height areformed at portions where the light reflection portions and capacitiveelements Cadd are formed.

[0139] Due to such a constitution, the difference in height of therespective pixel electrodes PX2 with respect to the transparentsubstrate SUB1 at these portions can be set to equal to or less than 0.1μm.

[0140] Accordingly, as shown in FIG. 5, it is needless to say that it isunnecessary to form the material layers DLM for adjusting heightrespectively at the portions where the light reflection portions areformed and at the portions where the capacitive elements Cadd areformed, that is, the material layers DLM for adjusting height can beformed either at the portions where the light reflection portions areformed or at the portions where the capacitive elements Cadd are formed.

Embodiment 3

[0141]FIG. 6 is a constitutional view showing still another embodimentof the liquid crystal display device of the present invention andcorresponds to FIG. 3 which shows the constitution of the embodiment 1.

[0142] In constitution, this embodiment differs from the embodiment 1shown in FIG. 3 in that a protective film PSV2 which is made of SiN, forexample, is further formed on an upper surface of the pixel electrodesPX2 and neither the protective film PSV nor the protective film PSV2 isprovided with opening portions OM.

Embodiment 4

[0143]FIG. 7 is a constitutional view showing still another embodimentof the liquid crystal display device of the present invention andcorresponds to FIG. 6 which shows the constitution of the embodiment 3.

[0144] In constitution, this embodiment differs from the embodiment 3shown in FIG. 6 in that both of the protective films PSV, PSV2 areprovided with opening portions and side walls of the protective filmsPSV2 are formed such that these side walls cover side walls of theprotective films PSV.

Embodiment 5

[0145]FIG. 8 is a constitutional view showing still another embodimentof the liquid crystal display device of the present invention andcorresponds to FIG. 6 which shows the constitution of the embodiment 3.

[0146] In the drawing, opening portions are formed in the protectivefilms PSV, while opening portions are not formed in the protective filmsPSV2.

Embodiment 6

[0147]FIG. 9 is a constitutional view showing still another embodimentof the liquid crystal display device of the present invention andcorresponds to FIG. 6 which shows the constitution of the embodiment 3.

[0148] In the drawing, both of the protective films PSV, PSV2 areprovided with opening portions and dislocations between the protectivefilms PSV, PSV2 are observed at the side walls of the openings withnaked eyes.

Embodiment 7

[0149] In the above-mentioned respective embodiments, the pixelelectrodes PX2 which also function as the reflection electrodes areformed as the pattern which has openings within the planar region. Sucha constitution brings about an advantageous effect that even when aphysical disconnection occurs at a portion of the pixel electrode PX2where a line width is narrow, the electrical separation can be obviated.

[0150] However, the present invention is not limited to theabovementioned constitution shown in respective embodiments and, asshown in FIG. 10A and FIG. 10B, it is needless to say that the pixelelectrodes PX2 which also function as the reflection electrodes can beformed using a pattern which cuts away portions of sides of the pixelelectrodes.

[0151] Due to such a constitution, even at a portion of the pixelelectrode PX2 where a line width is narrow, the portion can ensure thewidth wider than the line width of the portion of the pixel electrodePX2 in the previous embodiment and hence, the probability of theoccurrence of disconnection can be suppressed to a small value.

[0152] Further, in the above-mentioned respective embodiments, thecapacitive element which has one terminal thereof formed as the pixelelectrode has the other end thereof formed as the gate signal line GL.However, it is needless to say that the present invention is directlyapplicable to a constitution in which, for example, a capacitive elementline is formed separately from the gate signal line GL in the pixelregion and the capacitive element is formed between the capacitiveelement line and the pixel electrode.

[0153] In such a constitution, the capacitance element line is usuallyformed substantially in parallel to the gate signal line GL and exceptthat the capacitance element line exhibits the electric functiondifferent from the function of the gate signal line GL, the otherconstitution of the liquid crystal display device such as the layerstructure is exactly as same as the corresponding constitution of theprevious embodiments and hence, the present invention is applicabledirectly.

[0154] As can be clearly understood from the foregoing explanation,according to the liquid crystal display device of the present invention,the reduction of the contrast which is generated in the light reflectionmode can be drastically suppressed.

What is claimed is:
 1. A liquid crystal display device comprising pixelregions each of which is divided into a light reflection portion and alight transmission portion on a liquid-crystal-side surface of onesubstrate out of substrates which are arranged to face each other in anopposed manner while sandwiching liquid crystal therebetween, wherein oneach pixel region, a first light-transmitting pixel electrode which isformed on the light reflection portion and the light transmissionportion, a material layer which is formed on a major portion of thelight reflection portion, an insulation layer in which an opening isformed at the light transmission portion, and a second pixel electrodewhich is formed on the light reflection portion and also functions as areflection film are sequentially laminated.
 2. A liquid crystal displaydevice comprising pixel regions each of which is divided into a lightreflection portion and a light transmission portion on aliquid-crystal-side surface of one substrate out of substrates which arearranged to face each other in an opposed manner while sandwichingliquid crystal therebetween, wherein the pixel region is formed as aregion which is surrounded by a pair of gate signal lines and a pair ofdrain signal lines and includes a thin film transistor which is operatedin response to scanning signals from one gate signal line out of thepair of gate signal lines and first and second pixel electrodes to whichvideo signals from one drain signal line out of the pair of drain signallines are supplied through the thin film transistor, and on each pixelregion, the first light-transmitting pixel electrode which is formed onthe light reflection portion and the light transmission portion, amaterial layer which is formed on a major portion of the lightreflection portion, an insulation layer in which an opening is formed atthe light transmission portion, and the second pixel electrode which isformed on the light reflection portion and also functions as areflection film are sequentially laminated.
 3. A liquid crystal displaydevice comprising pixel regions each of which is divided into a lightreflection portion and a light transmission portion on aliquid-crystal-side surface of one substrate out of substrates which arearranged to face each other in an opposed manner while sandwichingliquid crystal therebetween, wherein the pixel region is formed as aregion which is surrounded by a pair of gate signal lines and a pair ofdrain signal lines and includes a thin film transistor which is operatedin response to scanning signals from one gate signal line out of thepair of gate signal lines and first and second pixel electrodes to whichvideo signals from one drain signal line out of the pair of drain signallines are supplied through the thin film transistor, on each pixelregion, the first light-transmitting pixel electrode which is formed onthe light reflection portion and the light transmission portion, amaterial layer which is formed on a major portion of the lightreflection portion, an insulation layer in which an opening is formed atthe light transmission portion, and the second pixel electrode which isformed on the light reflection portion and also functions as areflection film are sequentially laminated, and a total layer thicknessof the first pixel electrode and the material layer and a layerthickness of the gate signal line are respectively set to equal to orless than 100 nm.
 4. A liquid crystal display device comprising pixelregions each of which is divided into a light reflection portion and alight transmission portion on a liquid-crystal-side surface of onesubstrate out of substrates which are arranged to face each other in anopposed manner while sandwiching liquid crystal therebetween, whereinthe pixel region is formed as a region which is surrounded by a pair ofgate signal lines and a pair of drain signal lines and includes a thinfilm transistor which is operated in response to scanning signals fromone gate signal line out of the pair of gate signal lines and first andsecond pixel electrodes to which video signals from one drain signalline out of the pair of drain signal lines are supplied through the thinfilm transistor, on each pixel region, the first light-transmittingpixel electrode which is formed on the light reflection portion and thelight transmission portion, a material layer which is formed on a majorportion of the light reflection portion, an insulation layer in which anopening is formed at the light transmission portion, and the secondpixel electrode which is formed on the light reflection portion and alsofunctions as a reflection film are sequentially laminated, and thedifference between a total layer thickness of the first pixel electrodeand the material layer and a layer thickness of the gate signal line isset to equal to or less than 0.1 μm.
 5. A liquid crystal display devicecomprising pixel regions each of which is divided into a lightreflection portion and a light transmission portion on aliquid-crystal-side surface of one substrate out of substrates which arearranged to face each other in an opposed manner while sandwichingliquid crystal therebetween, wherein the pixel region is formed as aregion which is surrounded by a pair of gate signal lines and a pair ofdrain signal lines and includes a thin film transistor which is operatedin response to scanning signals from one gate signal line out of thepair of gate signal lines and first and second pixel electrodes to whichvideo signals from one drain signal line out of the pair of drain signallines are supplied through the thin film transistor, and on each pixelregion, the first light-transmitting pixel electrode which is formed onthe light reflection portion and the light transmission portion, anextension layer of a source electrode of the thin film transistor whichis connected to the first pixel electrode and is formed on a majorportion of the light reflection portion, an insulation layer in which anopening is formed at the light transmission portion, and the secondpixel electrode which is formed on the light reflection portion, isconnected to the source electrode through a contact hole formed in theinsulation layer and also functions as a reflection film aresequentially laminated.
 6. A liquid crystal display device comprisingpixel regions each of which is divided into a light reflection portionand a light transmission portion on a liquid-crystal-side surface of onesubstrate out of substrates which are arranged to face each other in anopposed manner while sandwiching liquid crystal therebetween, whereinthe pixel region is formed as a region which is surrounded by a pair ofgate signal lines and a pair of drain signal lines and includes a thinfilm transistor which is operated in response to scanning signals fromone gate signal line out of the pair of gate signal lines and first andsecond pixel electrodes to which video signals from one drain signalline out of the pair of drain signal lines are supplied through the thinfilm transistor, on each pixel region, the first light-transmittingpixel electrode which is formed on the light reflection portion and thelight transmission portion, an extension layer of a source electrode ofthe thin film transistor which is connected to the first pixel electrodeand is formed on a major portion of the light reflection portion, aninsulation layer in which an opening is formed at the light transmissionportion, and the second pixel electrode which is formed on the lightreflection portion, is connected to the source electrode through acontact hole formed in the insulation layer and also functions as areflection film are sequentially laminated, and the difference between atotal layer thickness of the first pixel electrode and the extensionlayer of the source electrode and a layer thickness of the gate signalline is set to equal to or less than 0.1 μm.
 7. A liquid crystal displaydevice comprising pixel regions each of which is divided into a lightreflection portion and a light transmission portion on aliquid-crystal-side surface of one substrate out of substrates which arearranged to face each other in an opposed manner while sandwichingliquid crystal therebetween, wherein the pixel region is formed as aregion which is surrounded by a pair of gate signal lines and a pair ofdrain signal lines and includes a thin film transistor which is operatedin response to scanning signals from one gate signal line out of thepair of gate signal lines and first and second pixel electrodes to whichvideo signals from one drain signal line out of the pair of drain signallines are supplied through the thin film transistor, on each pixelregion, the first light-transmitting pixel electrode which is formed onthe light reflection portion and the light transmission portion, amaterial layer which is formed on a major portion of the lightreflection portion, an insulation layer in which an opening is formed atthe light transmission portion, and the second pixel electrode which isformed on the light reflection portion and also functions as areflection film are sequentially laminated, and the second pixelelectrode is formed in a superposed manner on the other gate signal lineout of the pair of gate signal lines.
 8. A liquid crystal display devicecomprising pixel regions each of which is divided into a lightreflection portion and a light transmission portion on aliquid-crystal-side surface of one substrate out of substrates which arearranged to face each other in an opposed manner while sandwichingliquid crystal therebetween, wherein the pixel region is formed as aregion which is surrounded by a pair of gate signal lines and a pair ofdrain signal lines and includes a thin film transistor which is operatedin response to scanning signals from one gate signal line out of thepair of gate signal lines and first and second pixel electrodes to whichvideo signals from one drain signal line out of the pair of drain signallines are supplied through the thin film transistor, on each pixelregion, the first light-transmitting pixel electrode which is formed onthe light reflection portion and the light transmission portion, amaterial layer which is formed on a major portion of the lightreflection portion, an insulation layer in which an opening is formed atthe light transmission portion, and the second pixel electrode which isformed on the light reflection portion and also functions as areflection film are sequentially laminated, and the second pixelelectrode is formed in a superposed manner on the other gate signal lineout of the pair of gate signal lines, and a height adjusting materialwhich is provided for setting the difference between a height of thesecond pixel electrode with respect to the substrate in the lightreflection portion and a height of the second pixel electrode which isformed in a superposed manner on the other gate signal line with respectto the substrate is set to equal to or less than 0.1 μm is interposed atat least one of the light reflection portion or the other gate signalline.
 9. A liquid crystal display device comprising pixel regions eachof which is divided into a light reflection portion and a lighttransmission portion on a liquid-crystal-side surface of one substrateout of substrates which are arranged to face each other in an opposedmanner while sandwiching liquid crystal therebetween, wherein the pixelregion is formed as a region which is surrounded by a pair of gatesignal lines and a pair of drain signal lines and includes a thin filmtransistor which is operated in response to scanning signals from onegate signal line out of the pair of gate signal lines and first andsecond pixel electrodes to which video signals from one drain signalline out of the pair of drain signal lines are supplied through the thinfilm transistor, and on each pixel region, the first light-transmittingpixel electrode which is formed on the light reflection portion and thelight transmission portion, a material layer which is formed on a majorportion of the light reflection portion, an insulation layer which isformed on the light reflection portion and the light transmissionportion, and the second pixel electrode which is formed on the lightreflection portion and also functions as a reflection film aresequentially laminated.
 10. A liquid crystal display device comprisingpixel regions each of which is divided into a light reflection portionand a light transmission portion on a liquid-crystal-side surface of onesubstrate out of substrates which are arranged to face each other in anopposed manner while sandwiching liquid crystal therebetween, whereinthe pixel region is formed as a region which is surrounded by a pair ofgate signal lines and a pair of drain signal lines and includes a thinfilm transistor which is operated in response to scanning signals fromone gate signal line out of the pair of gate signal lines and first andsecond pixel electrodes to which video signals from one drain signalline out of the pair of drain signal lines are supplied through the thinfilm transistor, on each pixel region, the first light-transmittingpixel electrode which is formed on the light reflection portion and thelight transmission portion, a material layer which is formed on a majorportion of the light reflection portion, an insulation layer which isformed on the light reflection portion and the light transmissionportion, and the second pixel electrode which is formed on the lightreflection portion and also functions as a reflection film aresequentially laminated, and the difference between a total layerthickness of the first pixel electrode and the material layer and alayer thickness of the gate signal line is set to equal to or less than0.1 μm.
 11. A liquid crystal display device according to claim 1,further comprising a backlight.
 12. A liquid crystal display deviceaccording to claim 2, further comprising a backlight.
 13. A liquidcrystal display device according to claim 3, further comprising abacklight.
 14. A liquid crystal display device according to claim 4,further comprising a backlight.
 15. A liquid crystal display deviceaccording to claim 5, further comprising a backlight.
 16. A liquidcrystal display device according to claim 6, further comprising abacklight.
 17. A liquid crystal display device according to claim 7,further comprising a backlight.
 18. A liquid crystal display deviceaccording to claim 8, further comprising a backlight.
 19. A liquidcrystal display device according to claim 9, further comprising abacklight.
 20. A liquid crystal display device according to claim 10,further comprising a backlight.